Mich. Comp. Laws § 107.10
Repairs, alterations, and extensions may also be provided by the city council by contract for the making and installation of repairs, alterations, and extensions, which contract shall not impose a general obligation on the city, but which may provide for payment out of the net revenues, after payment of obligations due, provision for payment of obligations to become due, and payment of legitimate and necessary operating and other expenses, as shall become available from the operation of the works after completion of the repairs, alterations, or extensions and for retention of title to materials furnished in the seller until paid for in full. However, a contract made pursuant to this section shall not be construed to deprive the people of the city of any right vested in them by the constitution or the laws of this state, to constitute the granting of any franchise or its operating equivalent, or to convey title to property to any person not possessed of the title prior to the execution of the title retaining contract.
MCL 107.10